1. Field of the Invention
The present invention relates to an automatic arrangement apparatus and an electronic musical instrument for performing an automatic operation while arranging notes in real time and, more particularly, to a technique for automatically generating additional notes such as contrapuntal notes, countermelody notes and the like on the basis of melody notes.
1. Description of the Related Art
Conventionally, an electronic musical instrument For automatically generating additional notes such as countermelody notes on the basis of melody notes is known. For example, Japanese Patent Publication (Koukoku) No. 63-42274 discloses an electronic musical instrument, which selects and determines new countermelody notes from chord constituting notes for an accompaniment. The electronic musical instrument selects and determines new countermelody notes from chord constituting notes having a predetermined interval relationship with melody notes. Thus, countermelody tones harmonized with melody tones and having a full of musical expressions can be automatically produced.
A music piece has a chord progression based on a melody. In general, melody notes have a complicated sequence, and are normally selected from harmonic notes of corresponding chords but may sometimes be selected from nonharmonic notes. On the other hand, additional notes such as countermelody notes should be selected from harmonic notes of corresponding chords unless they are intentionally selected according to the music theory.
Therefore, in the prior art, since chord constituting notes having the predetermined interval relationship with melody notes are selected and determined as countermelody notes regardless of harmonic notes or nonharmonic notes, a countermelody note selected and determined based on a melody note as a nonharmonic note becomes an unexpected note against the music theory, and destroys a, chord, thus giving a musically unstable sense.
Further, U.S. Pat. No. 4,926,737 issued on May 22, 1990 discloses an automatic composer which extracts a nonharmonic tone from a melody. U.S. Pat. No. 4,508,002 issued on Apr. 2, 1985 discloses a method and apparatus which automatically generate an accompaniment tone according to a designated chord and a designated melody note.